Tangri river, also called Dangri river, originating in Shivalik Hills, is a tributary of Ghaggar river in of Haryana state of India.^[1][2]

The Tangri river originates in the Shivalik hills on the border of Haryana and Himachal Pradesh State, and flows along the haryana and Punjab, India border before meeting with Ghaggar river at the confluence.^[3] The basin is classified in two parts, Khadir and Bangar, the higher area that is not flooded in rainy season is called Bangar and the lower flood-prone area is called Khadar.^[3]

The Dangri or Tangri is a stream that rises in Morni Hills of the Siwalik Hills of south-eastern Himachal Pradesh in India,^[4] and flows for 70 km in Haryana.^[5] It confluences with the Markanda at Haryana-Punjab border north of Sadhpur Viran in northwest Kurukshetra district and south of Mehmudpur Rurki in south Patiala district. The combined Dangir-Markanda stream merges with the Sarsuti river in northeast Kaithal district east of Diwana and southwest of Adoya, before joining the Ghaggar river just east of Dhando village near Kasoli town in northwest Kaithal.^[4] It is thereafter known as the Ghaggar. Further downstream on the banks of the Ghaggar stands an old derelict fort at Sirsa town named Sarsuti.^[4] After the Ottu barrage, the Ghaggar river is called as Hakra river and in Sindh it is called Nara river. The order of rivers from left to right is Ghaggar, Dangri, Markanda and Sarsuti. Further left to right, Chautang and Somb rivers are tributaries of Yamuna.

It is believed that Sarsuti is a corruption of the word Sarasvati and that the 6–8 km wide channel of the Sarsuti–Ghaggar system might have once been the Sarasvati River mentioned in the Rig Veda.^[4][6] This Sarsuti channel is currently being revived by the Government of Haryana as the ancient Sarasvat river.

Originating from Morni Hills, Tangri confluences with its southern tributary called Balaiali river (which originates near south of Morni Hills) near Chajju Majra south of Kharar. Near Panjokhra southeast of Ambala the Tangri river divides in two streams that flow north and south of Ambala. Further downstream near Segti and Segta villages, Tangri river confluences with its tributary called Amri river (also known as Dadri river and Shahzadpur Wali river, originates near Rataur)) after Amri has already collected its own tributary called Omla river.^[7]

Several archaeologists have identified the old Ghaggar-Hakra River with the Sarasvati river, on the banks of which the Indus Valley Civilisation developed.^{[8][9][10][11]}